We all know the intake for the Max is a bit restrictive. CAI would be the best way to go, but drilling holes in my car's fender doesn't sit right with me. POP charger filters are loud, lousy on low end power and give you horable gas mileage. So I started to think - how can we get a bit more air into the intake system without sacraficing the above mentioned conditions? What about another intake path which would only open up when the draw was there. Perhaps a trap door? So here's what I've come up with.

First off I would like to thank Lime for the donation of her box.

The first thing I did was to see if there was an area which could be cut out to provide the air passage. The inside of the airbox doesn't have to many smooth or flat surfaces. So this was a bit tricky. The hole I cut was just below the stock port. This was the only area that was reasonably flat to accompany a trap door. I wanted the door to remain closed so if the stock scoop was to ram any air into the system on the highway I didn't want it to exit via this new intake path. The new air path should only be one way IN ONLY! And only open when there was a need. I wanted it to remain shut under normal driving conditions to minimize noise and provide normal air flow. But under hard accelleration it should open to let air in and growl a little.

To make the door I used a piece of 3mm tool box liner rubber. This was flexable enough yet heavy enough to be kept shut until the need for air was there. After some drilling, cutting, filing, and fitment issues the new trap door was finished. It's secured in place with a screw on one side and a notch on the other which fits into a slot in the airbox. This allowed it to open without any drag, just it's own weight keeps it closed. As soon as a vaccume is present in the airbox (do to restrictive piping on stock intake) this door will be pulled open to let air in.

Here's a few pics.

The hole

[IMG]ftp://jimmyb:2wtuvp6c@ftp.netwiz.net:21/public_html/Tom/airhole.JPG[/IMG]

Next was getting the door in place and making it stay closed, yet free enough to lift up when needed. This was the tricky part.

[IMG]ftp://jimmyb:2wtuvp6c@ftp.netwiz.net:21/public_html/Tom/trapdoor.JPG[/IMG]

I took this time to clean out my throttle body as well being I had the whole system out. I was suprised that it wasn't that bad at all. Just used a shop towel and some TB cleaner to wipe things clean. Then started it up and went for a test drive.

You can't hear any noise under normal driving conditions. Car sounds and feel exactly the same as it did before. BUT - If you put your foot down 1/2 way or more, the door definately opens up! There is a nice little growel to be heard, it's not much, but it's there! Just a throaty sound that wasn't there before. So onto the highway I go. As soon as I hit the entrance ramp I stoped the car. From a dead stop I step on it, right to the floor and hold. My door opens up immediately and the growl is there, which means more air is entering my engine! WAHOOO The trans (automagic) shifted at almost 6,300 RPM's and it was pulling hard all the way up there too. The shift was good and the power seemed to keep on coming. Before I knew it I had hit 80 MPH, 3rd gear just kicked in and I ran out of open space.

Overall I'm pleased with the outcome. Do I have more power??? Perhaps I do, only a dyno test will really prove if this works. The car definately feels stronger when you jump on it. Could this be from the immediate releaf of air starvation the stock intake has?
I think so.
Keeping the system as close to stock as possible has given me no losses, just minor gains with no drivability issues or excessive noise.

 

good idea but you are sucking in hot air right?

 

lol -wat happens if rocks get in there

 

I would suggest a little mesh from Home Depot to put over the hole to filter out the rocks leafs,and dust. Great idea NJMAX

 

IT should be okay w/o any mesh. It is still only letting air in before the filter. I removed the stock resonator from my factory ram air intake and it seemed to give a little more in the top end w/o sacrificing anything. I have since switched to the Stillen intake. You have a good idea and maybe you could connect a pipe to the new hole and route it towards cooler air???? Either way congrats on your cheap and effective mod.

 

I'll stick with OSCAI...

 

Thanks for the feedback guys. The hole is right on top of the engine mount so putting a pipe there isn't going to work. No room at all. Yes I am sucking in some warm engine bay air, but keep in mind that the factory "ram air" is still providing lots of cool air. So the mix of air when the door opens should still be on the cool side, not all hot air like a pop charger. I'll keep my eye on it for a while to make sure I'm not getting a lot of debri. Remember this only opens up under hard accelleration so it's not pulling air in all the time. Only when I want to play!

 

¬_¬ you mean my AIRbox.



I would put some fine mesh in there, probably...just to be on the safe side. We can test the difference for POP+ram versus that new box after Tuesday.

 

I'm thinking we need to do a run together soon.

 

anytime! "bring it!"

perfect use for devil face! :-p

 

You could also just tie up or tape up the stock filter to the top piece of the box, and just unbolt and remove the bottom piece. This is what i used to have and it sound just the same as an intake.

 

definitly get a piece of mesh under there just in case. Also i would use a nut/bolt combo to secure that trap door down better. Sounds like a good idea.
Im thinking about keeping the upper half of my cai installed and throwing a cone at the end of the MAF, and see what happenes. I lost alot of low end with my damn CAI, and even with my old Stillen HAI.

Ant

 

Steve (Frankencar Performance) is working on this now. Tuesday will bring more answers for the 4th gens.

 

Nifty idea, but my concern is the turbulence the flap causes when it opens. Aynone else see this as a problem? Another idea you might want to consider is routing a 2.5" vacumn hose from the right side of the airbox (if you were standing in front of the car). Route the house to the right of the battery and straight up to the headlight housing with the tube pointed down drawing in the cooler "bumper" air. I've got this setup on my car. I had the OSCAI setup along with this hose and the sound was awesome. I then reverted back to my HKS intake but left all the OSCAI tubing and lower intake box. I made a heatshield so that all the cool air funnels around the filter.

That reminds, I need to tell Frankencar that they can't steal my heatshield design As far *** I know, I;m the only Maxima running a heatshield on the intake (1 year now).


Dave

 

I think you guys are all nuts. Low end power loss with JWT/Stillen is neglegible (sp?) at best. I myself kept the lower portion of my stock air box on that now supports my JWT intake which could be one of the reasons why my low end has little to no loss. Anyone done this with different results? Is this just varying by car? I don't get how you guys complain so much about losing low end power.
The small power I do lose is more than made up for by the power I gain at full throttle. So, what's the dilly? (yo?)

 

I've been wanting to do a heat shield on my Max for some time. I've considered relocating the battery too - thinking it would make it easier to make a cold air box. I've decided against the battery relocation for co$t concerns but plan to tackle the project as soon as the weather gets nicer. (no garage) DO you have any pics? Thanks.

 

Dave B, do you have a picture of that intake with the vacuume hose? As far as turbulents, the flap is pretty solid and will only open up a small bit to let some air sneak in to overcome any vacuume in the airbox. Vacuume in the airbox would be caused by any restrictions in the stock ram air piping. Also, the air is entering the box in the same area and direction as it's supposed to come in. So I don't think turbulance could be an issue. I do see your piont though.
I was playing today with the car it does seem to pull just a bit harder when you open it up. And I'm liking the sound too!! Like I mentioned before the only proof would be in a dyno compare. But in theory what I've done makes sense. Give the intake more air only when it's needed and if the ram air does indeed work at 60MPH then keep the door shut. I'll play more with my right foot for the next few days.

 

{waves to stock airbox} How you doin'?

 

[STOCK AIR BOX TALKING] I miss you baby but my new owner has done some cool stuff to me. [/STOCK AIR BOX TALKING]